This invention relates to an improved structure of a vehicular temperature, pressure and vacuum meter which mainly comprises a meter body, a Bourdon tube, a fast-removable hand rod and a dial plate, in particular, the dial plate, the Bourdon tube and the fast-removable hand rod can be assembled without using any bolts and screws. Besides, before mass production, manufacture and assemblage, it is not necessary to consider the specification requirements for the sizes of the dial plates, while the test of sensitivity and accuracy of the Bourdon tube corresponding to the indication hand of the fast-removable hand rod can be completed at the same time, thus the retaining recess on the dial plate is fitted perfectly in place to the retaining protruding point on the housing.
In most cases, the temperature, pressure and vacuum meter takes the advantage of the Bourdon tube for detecting variation of temperature, air pressure or vacuum under a certain working condition to ensure the mechanical safety in vehicles. That is, when the circular copper tube fixed on the housing senses the changes of working environment, the expansion and contraction thus generated will drive the driving mechanism, and move the indication hand to display the resultant changes in temperature, pneumatic pressure, hydraulic pressure and vacuum physically taking place in this working environment.
As shown in FIG. 4, the components of the prior art of temperature, pressure or vacuum meter include the housing 14, the Bourdon tube 4, indication hand 5, and the dial plate 2, wherein the Bourdon tube 4 has a bracket 41, a circular copper tube 42, a drive mechanism 43, a vent tube 45 and connecting rack 47. The top of the bracket 41 is welded to the vent tube 45 and the circular copper tube 42, and one end of circular copper tube 42 is welded to the drive mechanism 43 to form an integral part. The drive mechanism 43 is long bent copper wire with one end bent into clevis bolted to the connector 46 on the back of the dial plate 2. By means of the screw hole 48 on the connecting rack 47, the dial plate 2 is fixed to the completed Bourdon tube 4 and the indication hand 5 is welded to the connector 46. As a matter of fact, the prior art of the temperature, pressure and vacuum meter is not an ideal design, which brings forth many problems in the production line as described below:
1. Multiplicity in components and complicity in assembly for the Bourdon tube leads to high production cost.
In the assembly process, it takes welding and bolting operation to put the Bourdon tube, the dial plate and the hand rod via the connector and the connecting rack. Such a process implies directly the laborious complicity in assembly, and indirectly the higher production cost. The fast-removable hand rod is an integral form, easy and swift to be assembled to the Bourdon tube and the dial plate. The problem occurred in the prior art will never happen in this invention.
2. The Bourdon tube and the hand rod can never be assembled, adjusted and tested beforehand.
In manufacturing the prior art of the temperature, pressure and vacuum meter, the hand rod has to pass an aperture on the dial plate to be welded to the Bourdon tube and finally to be test for its sensitivity and accuracy. In particular, the dial plate varies in size and color, so it is impossible to shorten the production time and reduce the production cost because these three components are not allowed to be assembled beforehand. This invention proposes an integrally designed fast-removable hand rod, so the difficulties encountered in the prior art are eliminated. The assemblage, production as well as the adjustment of sensitivity and accuracy of the Bourdon tube corresponding to the fast-removable hand rod can be proceeded without regard to the size and color of the dial plate.
To this end, the inventor has spent for years the efforts to seeking better solution to come up with an improved structure for the vehicular temperature, pressure and vacuum meter having high value and novel characteristics.
The main object of this invention is to provide an improved structure for the vehicular temperature, pressure and vacuum meter equipped with a unique dial plate, irrespective of size and color. This design permits fast assembly, manufacture and test beforehand for its sensitivity and accuracy.
Another object of this invention is to provide a substantially simplified procedure for assembly and manufacture of the vehicular temperature, pressure and vacuum meter in which the hand shaft of the integrally formed hand rod is inset to the aperture of the bracket of the Bourdon tube and the dial plate is infixed to the housing with no welding and bolting process.
Another object of this invention is to provide an integrally formed hand rod, saving the cost of the connector, connecting rack, screw and bolt.
Many changes and modifications in the above disclosed embodiment of the invention can, of course, be carried out without departing from the scope thereof. Accordingly, to promote the progress in science and the useful arts, the invention is disclosed and is intended to be limited only by the scope of the appended claims.